.tab {
    position: relative;
     overflow: hidden;   
}

.all {
    margin: 30rpx 0;
    text-align: center;
    font-weight: 900;
    font-size: 50rpx;
    font-family: "黑体";
    color: #898989;
    background: -webkit-linear-gradient(45deg, #39eef6, #f86527, #fcd72d, #5f2cf8, #bed5f5);
    color: transparent;
    /*设置字体颜色透明*/
    -webkit-background-clip: text;
    /*背景裁剪为文本形式*/
    animation: ran 10s linear infinite;
    /*动态10s展示*/
}

@keyframes ran {
    from {
        backgroud-position: 0 0;
    }
    to {
        background-position: 2000px 0;
    }
}
